Oxygen diluter system



United States Patent [72] lnventor August Oroza Tustin, California [2|]Appl. No. 413,801

[22] Filed [45] Patented [73] Assignee Nov. 25, l964 Sept. 1, 1970Robertshaw Controls Company Richmond, Virginia a corporation of Delaware[54] OXYGEN DILUTER SYSTEM 10 Claims, 3 Drawing Figs.

63, 64, 604; l28/l42, 142.2, 202, 203; l37/8l, 111, I14; l38/46 [56]References Cited UNITED STATES PATENTS 2,269,500 l/l942 Wildhack 128/191BASIC OXYGEN REGULATOR o SUPPLY 2,616.442 11/1952 Holmes 12X/l42XFOREIGN PATENTS 47l,385 2/1929 Germany .t 128/203 724929 2/l955 GreatBritain HIS/203 126,236 6/1959 U.S.S.R 137/63(R)UX PrimaryExaminer-William F. ODea Assistant Examinen-R. Gerard Attorney-AuzvilleJackson Jr., Robert L. Marben and Anthony A. OBrien ABSTRACT: An oxygendiluter system for breathing apparatus including a demand type regulatorfor the oxygen DILUTER SYSTEM OXYGEN-NR MIXTURE Patented Sept. 1, 1970DI LUTER SYSTEM MIXTURE mm N E G w 0 BASIC OXYGEN REGULATOR FIG!INVENTOR AUGUST OROZA BY M M m FIG.3

ATTORNEY OXYGEN DILUTER SYSTEM The present invention relates tobreathing apparatus and, more particularly, to an oxygen regulator anddiluter system of the type utilized in high altitude and space flights.

Some aircraft oxygen systems presently used in high altitude flyingprovide 100 percent oxygen from the moment they are put in use; however,from both a physiological viewpoint and an economical viewpointregarding oxygen consumption during long flights, it is highly desirableto furnish automatically a varying proportion of oxygen as a function ofaltitude. There are certain conventional systems now in use includingpanel mounted regulator systems as well as man mounted regulator systemswhich provide for dilution of oxygen and air in a varying proportion inaccordance with atmospheric pressure variations, i.e., from a proportionof 100 percent oxygen and percent air under high altitude flightconditions where 100 percent oxygen is required for breathing purposesto a proportion of 0 percent oxygen to 100 percent air under lowaltitude flight conditions where only normal air is needed for breathingpurposes.

The basic problem of dilution has been approached by injecting air intoa mixing chamber and includes a nozzle for the oxygen flow. However, ina demand type regulator system, the regulator fails to achieve peak flowand the overall stability of the system is adversely affected becausethe nozzle back pressure, i.e., the nozzle restriction downstream of themain demand valve increases the nozzle back pressure. In order toobtainadequate dilution ratios, the amount of nozzle restriction is high bynecessity but when operating on a 100 percent oxygen flow, thisdownstream restriction impedes the flow and produces the nozzle backpressure resulting in severe oscillations.

It is, therefore, an object of the present invention to eliminateoscillations in an oxygen diluter system of the air injector type.

Another object of this invention is to proportion the flow of oxygen asa function of atmospheric pressure in an oxygen diluter system of theair injector type without undue restriction of the oxygen flow.

This invention has another object in that a variable orifice controlsoxygen flow in an oxygen diluter system of the air injector type.

The present invention has another object in that a variable area nozzlein an oxygen diluter system varies its cross sectional flow area as afunction of oxygen flow over the entire dilution range where the oxygenflow varies as a function of demand sensed by a demand oxygen regulator.

It is another object of the present invention to contour the poppet ofvariable area nozzle in an oxygen diluter system so that the contourprofile produces the injection effect for drawing air into the system.

A further object of the present invention is to dampen vibrations in avariable nozzle arrangement of the piston-cylinder type in an oxygendiluter system ofthe air injector type.

The present invention has a still further object in that a variablenozzle automatically varies it cross sectional flow area in response tooxygen flow in an oxygen diluter system to provide a considerable jetvelocity having a high injector efficiency with a large air drawingpower at increasing rates of flow within dilution ranges.

In accordance with the present invention, a preferred embodiment of anoxygen diluter system for breathing apparatus includes oxygen regulatingmeans for regulating an oxygen flow in accordance with demand, aircontrol means for controlling an air flow as a function of atmosphericpressure. a mixture chamber for mixing the oxygen and air flows, andorifice means operatively disposed downstream of the oxygen regulatingmeans and being automatically varied as a function of the oxygen flow.

Other objects and advantages of the present invention will becomeapparent from the following description of a preferred embodiment, takenin connection with the accompanying drawing wherein:

FIG. 1 is a schematic diagram of an oxygen diluter system embodying thepresent invention;

FIG. 2 is a top view ofa part of FIG. 3; and FIG. 3 is a partial crosssection of a breathing apparatus control embodying the system of HO. 1.

With reference to FIG. 1 of the drawing, a basic oxygen regulator deviceof the demand type includes a hollow body 10 having a peripherallysealed diaphragm 12 separating the body 10 into two chambers 14 and 16.The chamber 16 is vented at 18 to the atmosphere to define anatmospheric chamber and the chamber 14 has an inlet port 20 which isconnected to a suitable oxygen supply.

Adjacent the inlet port 20, a valve member 22 controls the flow ofoxygen into the chamber 14; a valve stem 24 has one end connected to thevalve element 22 and an opposite end connected to one side of thediaphragm 12, which may be inherently spring biased or which may beprovided with a biasing spring in the chamber 16 acting on the otherside of the diaphragm. Movement of valve element 22 is effected by apressure differential between chambers 14 and 16; such differentialvaries in accordance with atmospheric pressure in chamber 16 and inaccordance with oxygen pressure variations established by demand of theuser. Chamber 14 is thus designated as a demand chamber and has a demandsensing port 26 and an outlet port 28.

The diluter part of the breathing apparatus control includes a hollowcasing 30 having an outlet 32 adapted to be connected to the breathingdevice such as a helmet or face mask (not shown). The outlet 32 extendsfrom a mixture chamber 34 which communicates with the demand chamberoutlet port 28 by means of an opening or orifice 36. Oxygen flow throughthe orifice 36 is varied by a properly contoured poppet 38 formed on oneend of a hollow, cylindrical stem 40 that is opened on its opposite end.The stem 40 extends through the open end of an aligned cylinder 42 whichis centrally supported by a plurality of spider arms 44 spaced about theouter wall of cylinder 42 and attached to the adjacent internal wallportions of casing 30. The spider arms 44 are properly contoured toprovide streamline flow therearound. Opposite its opened end, thecylinder 42 is closed by a bottom wall 46 having a central aperturesuitably threaded to receive the threaded end of an adjusting rod 48.The adjusting rod 48 extends into the cylindrical space defined by thestem 40 and cylinder 42; a coil spring 50 encircles the inner end ofadjusting rod 48 and is mounted in compression between the inner surfaceof poppet 38 and a fixed collar on the rod 48. With such an arrangementthe biasing force of the coil spring 50 may be adjusted by rotation ofthe adjusting rod 48 which is located on a longitudinal axis defined bythe centrally aligned axis of the outlet 32, the mixture chamber 34 andthe orifice 36.

As is illustrated in FIG. 3, the mixture chamber 34 communicates with anair flow chamber 52 which is controlled by a one-way check valve 54being made of suitable flexible material so as to be pressureresponsive. The valve 54 is centrally attached to a ported valve plate56 that is securely fastened to a shoulder 58 formed in an internal wallportion of casing 30. The ported valve plate 56 separates the air flowchamber 52 from an air chamber 60 and air flow therethrough iscontrolled by the valve 54 in accordance with a differential pressurebetween chamber 52 and chamber 60. In addition to the one-way checkvalve 54, the ported valve plate 56 is separately controlled by a valvedisc 62 secured to the bottom wall of an aneroid bellows 64. The topwall of bellows 64 carries an adjusting screw 66 which is threadedthrough a suitably threaded opening centrally disposed on a fixed coverplate 68. The bellows 64 thus has one end adjustably fixed in thechamber 60 and an opposite end with valve 62 thereon being movablerelative to the valve plate 56 in response to atmospheric pressurevariations in the chamber 60.

The cover plate 68 is provided with three equally circumferentiallyspaced air inlet openings 70 (only one being shown in FIG. 3) which arecontrolled by a manually movable closure plate 72. As shown in FIG. 2,the closure plate 72 is provided with three equally circumferentiallyspaced air ports 74 which are alignable with the inlet openings 70 inthe fixed cover plate 68. A central opening 76 in the closure plate 72permits access to the adjusting screw 66 and defines an axis of rotationfor the closure plate 72 which is rotated by a lever arm 78 projectingradially outwardly from the circumference thereof. Adjacent itsperiphery, the closure plate 72 is provided with a plurality (four) ofarcuate slots 80 and a similar plurality (four) of headed fasteners 82which have threaded shanks (not shown) extending freely through theirrespective slots 80. The heads of the threaded fasteners 82 are largerthan the width of the slots 80 and the threaded shanks extend throughaligned openings in the fixed cover plate 68 and terminate in threadedbores (not shown) in a flange portion of the casing 30. The threadedfasteners frictionally clamp the closure plate 72 to the fixed coverplate 68 to prevent accidental movement thereof; however, the closureplate 72 may be moved by the manual lever 78 whereby the closure plate72 slides on the fixed cover plate 68 for selectively positioning theair ports 74 in and out of registery with the inlet openings 70.

In the following description of a sequence of operation of the presentinvention, it is to be noted that any suitable type of basic oxygenregulator control may be utilized and the schematic arrangement of suchcontrol has been over-simplified in FIG. 1 for the sake of brevity.Accordingly, it is assumed that an oxygen regulator of the demand typeis being used; i.e., the oxygen valve 22 is opened and closed inaccordance with the demand sensed at the regulators demand chamber 14whereby the control position of the oxygen valve 22 is'accordinglyvaried with inhalation and exhalation at the face mask. Thus, the flowof oxygen is zero at the start of inhalation, rises to a maximum duringinhalation, then decreases to zero and remains zero during exhalation.

Assuming now that there is no demand for oxygen, the oxygen valve 22 isclosed and the atmospheric pressure in aneroid chamber 60 causescontraction of the bellows 64 whereby the valve disc 62 is displacedfrom the ported valve plate 56. Under such conditions, the controllingcomponents are positioned as shown in FIG. 3, i.e., since there is nooxygen flow, the poppet 38 is biased to its extreme position ofsubstantially closing the orifice 36. During inhalation at the facemask, the pressure in chamber 52 is decreased and the differentialpressure between chambers 60 and 52 causes the one-way valve 54 to openand air is drawn through the aligned openings 74 and 70, chamber 60,ported valve plate 56 and chamber 52 to the mixture chamber 34; thuspercent oxygen and 100 percent air is delivered to the outlet 32. As iswell known in the art, the face mask includes some form of exhalationvalve to expel exhaled air to the atmosphere rather than back throughthe outlet 32. Such exhalation increases the pressure in chamber 52 sothat the valve 54 closes the ported valve plate 56.

Under conditions ofhigh altitude where 100 percent oxygen is needed, theatmospheric pressure in chamber 60 causes expansion of bellows 64whereby the valve disc 62 closes the ported valve plate 56 so there isno air flow. At the same time the oxygen valve 22 is positioned inresponse to inhalation and exhalation at the face mask. During suchconditions, 0 percent air and I00 percent oxygen is delivered from thechamber 14 and through the orifice 36 and the pressure of such flowdisplaces the poppet 38 against the bias of the coil spring 50 so thatthere is substantially no restriction downstream of the demand chamber14.

Turning now to conditions of an intermediate altitude or conditions of avarying altitude. the oxygen regulator device supplies a flow of oxygento outlet port 28 as a function of the face mask demand and the airinlet control valve 62 is opened by the contraction of bellows 64 inresponse to atmospheric pressure. The pressure of the oxygen flow actingon the contoured poppet head 38 moves the piston stem 40 inwardly in thecylinder 42 which guides such stem movement; should there by any abruptchanges or line pressure variations, the coil spring 50 acts as a damperto prevent oscillation or hunting of the head 38 in the orifice 36 andto assure a smooth stable movement of the head 38 in automaticallyresponding to the oxygen flow. Movement of the hemi-sphericallycontoured head 38 varies the cross-sectional flow area of the orifice 36and the head 38 is contoured in such a manner that under the influenceof the forces acting on it by the pressure differential, thehydrodynamic forces and the spring force, the piston 3840 seeks abalanced position. In such balanced position, the hemi-sperical contouron the head 38 results in a high velocity jet of oxygen flow into themixture chamber 34. The high velocity jet causes a reduced pressure inthe chamber 52 whereby the one-way valve 54 is flexed to an openposition and air is induced to flow through the ported valve plate 56and into the mixture chamber 34 where it is entrained with the oxygenflow; the mixture then flows through the outlet 32 for supplying thebreathing apparatus.

As the oxygen flow increases and the pressure downstream of theregulator valve correspondingly increases, the piston 3840 attains a newequilibrium position which by the hemispherical profile of head 38increases the flow area of the orifice 36 whereby the velocity of thejet is maintained without appreciable change in back pressure. When thedemand of oxygen in the regulator sensing conduit 26 determines that theregulator 10 must deliver a large quantity of oxygen, such as when thereis no air flow through the ported valve plate 56, the poppet head 38senses the large increase in force due to nozzle back pressure andresponds by increasing the flow area of orifice 36; thus the pressuredownstream of the regulators demand valve is relieved and the regulatorattains full flow capacity free of oscillation.

In the above arrangement the orifice 36 and the biased piston 38-40 withits slide guide constitutes a variable area nozzle assembly whichresponds automatically to oxygen flow from the demand regulator 10 forestablishing a high velocity jet flow that produces the air injectioneffect necessary to provide dilution over the entire range of dilutionproportions. By establishing a high jet velocity, the variable areanozzle 0btains large air drawing power at increasing rates of flowwithin the range desired for dilution levels at a relatively highinjector efficiency because the unfavorable conditions of high nozzleback pressure is minimized. The above arrangement presents theadditional advantage in that when high flows of oxygen are required andthe dilution system is no longer required (as at high altitudes), thenozzle is practically removed from the system due to the increased flowarea at the orifice and the practically unrestricted flow of 100 percentoxygen to the outlet 32.

In accordance with the present invention, the oxygen diluter system maybe manually controlled to provide I00 percent oxygen regardless ofaltitude or atmospheric pressure. in such an instance, the manuallyoperated lever 78 is rotated clockwise as viewed in FIG. 2 to a positionwhere the fasteners 82 engage the opposite edges of the correspondingslots thus the ports 74 are moved out of registry with the openings 70and the flow of air to the aneroid chamber 60 is cut-off. The systemthen operates as described above when valve 62 cuts off the intake airflow and percent oxygen is delivered to the outlet 32.

Inasmuch as the preferred embodiment of the present invention is subjectto many variations, modifications and changes in detail, it is intendedthat all matter contained in the foregoing description or shown on theaccompanying drawing shall be interpreted as illustrative and not in alimiting sense.

lclaim:

1. ln an oxygen diluter system for breathing apparatus, the combinationcomprising:

oxygen regulating means having demand valve means for regulating anoxygen flow in accordance with oxygen demand variations;

means defining a mixture chamber for mixing an air flow with the oxygenflow;

air control means having first valve means operative in response toatmospheric pressure variations for controlling an air fiow and secondvalve means operative in response to pressure conditions of the oxygenflow in the mixture chamber;

variable nozzle means automatically controlling the oxygen flow into themixture chamber in response to pressure variations of the oxygen flowfrom the demand valve means; and

said variable nozzle means controlling the oxygen flow into the mixturechamber in a manner to effect a variable jet velocity resulting in acorresponding variable pressure condition in the mixture chamber foractuating said second valve means.

2. The combination as recited in claim 1 wherein said variable nozzlemeans includes an orifice opening and a nozzle head movable to vary theflow area of the orifice opening.

3. The combination as recited in claim 2 wherein said nozzle head has ahemi-spherical contour.

4. In an oxygen diluter system for breathing apparatus, the combinationcomprising:

an oxygen regulator having oxygen flow inlet and outlet ports and demandvalve means for regulating an oxygen flow therebetween in accordancewith oxygen demand variations; an air diluter casing having a mixturechamber and outlet means adapted to be connected to breathing apparatus;

intake air control means having pressure responsive valve means forcontrolling an air flow in response to atmospheric pressure variationsand having injector valve means downstream of said pressure responsivevalve means for controlling the air flow to said mixture chamber;

variable orifice means in said casing automatically varying the velocityof the oxygen flow into said mixture chamber; and

said injector valve means being actuated from its closed position inaccordance with pressure variations accompanying the velocity variationsof the oxygen flow in said mixture chamber.

5. The combination as recited in claim 4 wherein said varia ble orificemeans includes an orifice defining a flow area and nozzle head meansbeing automatically positioned relative to the orifice in response tothe oxygen flow through the flow area, said nozzle head means beingmovable through a plurality of positions corresponding to a range ofoxygen-air dilution proportions from 0 percent oxygen and lOO percentair to percent oxygen and 0 percent air whereby the flow area is variedthrough a corresponding range from a substantially full restricted flowarea for a 0 percent oxygen flow to a substantially unrestricted flowarea for a 100 percent oxygen flow.

6. The combination as recited in claim 5 wherein said intake air controlmeans further comprises manually operated means for selectively cuttingoff air flow to the mixture chamber.

7. The combination as recited in claim 4 wherein said variable orificemeans includes an orifice opening and nozzle head means movable to varythe flow area of the orifice means in response to pressure of the oxygenflow therethrough.

8. The combination as recited in claim 7 wherein said nozzle head meansincludes a head portion and a stem portion and means for guidingmovement of said stem portion.

9. The combination as recited in claim 8 wherein said stem portionincludes a hollow stem opened at one end and said guiding meanscomprises a cylinder having one opened end slidably receiving saidhollow stem and having support ribs attached to said casing in saidmixture chamber.

10. The combination as recited in claim 9 wherein said cylinder includesbiasing means acting on said hollow stem and adjusting means to adjustsaid biasing means.

